+ lib-stackdepot-add-helper-to-print-stack-entries.patch added to -mm tree

+ lib-stackdepot-add-helper-to-print-stack-entries.patch added to -mm tree

[akpm]

The patch titled
     Subject: lib, stackdepot: add helper to print stack entries
has been added to the -mm tree.  Its filename is
     lib-stackdepot-add-helper-to-print-stack-entries.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/lib-stackdepot-add-helper-to-print-stack-entries.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/lib-stackdepot-add-helper-to-print-stack-entries.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Imran Khan <imran.f.khan@oracle.com>
Subject: lib, stackdepot: add helper to print stack entries

To print a stack entries, users of stackdepot, first use stack_depot_fetch
to get a list of stack entries and then use stack_trace_print to print
this list.  Provide a helper in stackdepot to print stack entries based on
stackdepot handle.  Also change above mentioned users to use this helper.

Link: https://lkml.kernel.org/r/20210915014806.3206938-3-imran.f.khan@oracle.com
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/stackdepot.h |    2 ++
 lib/stackdepot.c           |   18 ++++++++++++++++++
 mm/kasan/report.c          |   15 +++------------
 mm/page_owner.c            |   13 ++++---------
 4 files changed, 27 insertions(+), 21 deletions(-)

--- a/include/linux/stackdepot.h~lib-stackdepot-add-helper-to-print-stack-entries
+++ a/include/linux/stackdepot.h
@@ -25,6 +25,8 @@ depot_stack_handle_t stack_depot_save(un
 unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 			       unsigned long **entries);
 
+void stack_depot_print(depot_stack_handle_t stack);
+
 unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
 
 #ifdef CONFIG_STACKDEPOT
--- a/lib/stackdepot.c~lib-stackdepot-add-helper-to-print-stack-entries
+++ a/lib/stackdepot.c
@@ -215,6 +215,24 @@ static inline struct stack_record *find_
 }
 
 /**
+ * stack_depot_print - print stack entries from a depot
+ *
+ * @stack:		Stack depot handle which was returned from
+ *			stack_depot_save().
+ *
+ */
+void stack_depot_print(depot_stack_handle_t stack)
+{
+	unsigned long *entries;
+	unsigned int nr_entries;
+
+	nr_entries = stack_depot_fetch(stack, &entries);
+	if (nr_entries > 0)
+		stack_trace_print(entries, nr_entries, 0);
+}
+EXPORT_SYMBOL_GPL(stack_depot_print);
+
+/**
  * stack_depot_fetch - Fetch stack entries from a depot
  *
  * @handle:		Stack depot handle which was returned from
--- a/mm/kasan/report.c~lib-stackdepot-add-helper-to-print-stack-entries
+++ a/mm/kasan/report.c
@@ -132,20 +132,11 @@ static void end_report(unsigned long *fl
 	kasan_enable_current();
 }
 
-static void print_stack(depot_stack_handle_t stack)
-{
-	unsigned long *entries;
-	unsigned int nr_entries;
-
-	nr_entries = stack_depot_fetch(stack, &entries);
-	stack_trace_print(entries, nr_entries, 0);
-}
-
 static void print_track(struct kasan_track *track, const char *prefix)
 {
 	pr_err("%s by task %u:\n", prefix, track->pid);
 	if (track->stack) {
-		print_stack(track->stack);
+		stack_depot_print(track->stack);
 	} else {
 		pr_err("(stack is not available)\n");
 	}
@@ -214,12 +205,12 @@ static void describe_object_stacks(struc
 		return;
 	if (alloc_meta->aux_stack[0]) {
 		pr_err("Last potentially related work creation:\n");
-		print_stack(alloc_meta->aux_stack[0]);
+		stack_depot_print(alloc_meta->aux_stack[0]);
 		pr_err("\n");
 	}
 	if (alloc_meta->aux_stack[1]) {
 		pr_err("Second to last potentially related work creation:\n");
-		print_stack(alloc_meta->aux_stack[1]);
+		stack_depot_print(alloc_meta->aux_stack[1]);
 		pr_err("\n");
 	}
 #endif
--- a/mm/page_owner.c~lib-stackdepot-add-helper-to-print-stack-entries
+++ a/mm/page_owner.c
@@ -394,8 +394,6 @@ void __dump_page_owner(const struct page
 	struct page_ext *page_ext = lookup_page_ext(page);
 	struct page_owner *page_owner;
 	depot_stack_handle_t handle;
-	unsigned long *entries;
-	unsigned int nr_entries;
 	gfp_t gfp_mask;
 	int mt;
 
@@ -423,20 +421,17 @@ void __dump_page_owner(const struct page
 		 page_owner->pid, page_owner->ts_nsec, page_owner->free_ts_nsec);
 
 	handle = READ_ONCE(page_owner->handle);
-	if (!handle) {
+	if (!handle)
 		pr_alert("page_owner allocation stack trace missing\n");
-	} else {
-		nr_entries = stack_depot_fetch(handle, &entries);
-		stack_trace_print(entries, nr_entries, 0);
-	}
+	else
+		stack_depot_print(handle);
 
 	handle = READ_ONCE(page_owner->free_handle);
 	if (!handle) {
 		pr_alert("page_owner free stack trace missing\n");
 	} else {
-		nr_entries = stack_depot_fetch(handle, &entries);
 		pr_alert("page last free stack trace:\n");
-		stack_trace_print(entries, nr_entries, 0);
+		stack_depot_print(handle);
 	}
 
 	if (page_owner->last_migrate_reason != -1)
_

Patches currently in -mm which might be from imran.f.khan@oracle.com are

lib-stackdepot-check-stackdepot-handle-before-accessing-slabs.patch
lib-stackdepot-add-helper-to-print-stack-entries.patch
lib-stackdepot-add-helper-to-print-stack-entries-into-buffer.patch